Apparatus for the selective holding of a to-and-fro driven control element of a textile machine in one of its terminal position

ABSTRACT

An apparatus for the selective holding of a to-and-fro driven control element of a textile machine in one of its terminal positions, wherein there is provided a holding element constructed as an armature of a selectively energizable electromagnet, this holding element, when the electromagnet is not energized, moves from a first position, in which it bears against the electromagnet into a second position and that in one of its positions blocks the control element located in the one terminal position. An actuation mechanism or device acts upon the holding element in order to bring the holding element from its second position into its first position and/or to raise the holding element bearing against the electromagnet from such electromagnet when it is not energized.

United States Patent Speich Apr. 1, 1975 3.749.935 7/l973 Warren 307/l4) Primary ExuminerL. T. Hix Attorney. Agent, or Firm-Diller, BrownRamik 84 POSITION Wight [75] Inventor. Franz Speich. Frick, Switzerland57 ABSTRACT I73] Assignee: 1MB lngenleurburs fur l 1 Maschinenbau JakobM ll r, F i k An apparatus for the selective holding of a to-and-fro Swil d driven control element of a textile machine in one of its terminalpositions wherein there is provided a [221 1973 holding elementconstructed as an armature of a selec- [21] A l No; 427,625 tivelyenergizable electromagnet, this holding element when the electromagnetis not energized, moves from a first position, in which it bears againstthe electro- Forelgn Apphfamm Prmmy Dam magnet into a second positionand that in one of its J'tIlL IU, SWIIZCl'IUnd t t t i t t t positionsblocks the ontrol element lgcated in [he one terminal position. Anactuation mechanism or de- L.S. (,I. t t t v t t ricg acts upon theholding element in rder to bring 'f Cl H05 the holding element from itssecond position into its Field of SlalTh 317/262 R3 307/l49- 154 firstposition and/or to raise the holding element bearing against theelectromagnet from such electromagl l Rtfferences cued net when it isnot energized.

UNITED STATES PATENTS mien: 7/1933 Paris 317/262 R 13 8 Drawmg figures7- 4 2 3 70 l} l l 2% 5 l r' 'p 3 7\ l! 2 a I I 5 m- AN H.575

SILU 2 6F 5 A 13cB APPARATI'S FOR THE SELECTIVE HOLDING ()F A TO-AND-FRODRIVEN CONTROL ELEMENT OF A TEXTILE MACHINE IN ONE OF ITS TERMINALPOSITION BACKGROUND OF THE INVENTION The present invention relates to anew and improved construction of apparatus for selectively fixedlyholding a to-and-fro driven control element of a textile ma chine in oneof its terminal positions.

SUMMARY OF THE INVENTION It is a primary object of the present inventionto provide an apparatus of the previously mentioned type which is simplein construction. operates in a relatively disturbance-free manner andwhich is not associated with any undesired limitations in the operatingspeed of the textile machine.

Another object of the present invention aims at the provision of animproved construction of apparatus for the selective holding of ato-and-fro driven control element of a textile machine in one of itsterminal positions. wherein such apparatus is relatively simple inconstruction and design. extremely reliable in operation. and notreadily subject to malfunction or breakdon it.

Now in order to implement these and still further objects of theinvention. which will become more readily apparent as the descriptionproceeds. the apparatus of the previously mentioned type and ascontemplated by the invention comprises a holding element constructed asan armature of a selectively cnergizable electromagnet. wherein when theelectroniagnet is not energized this holding element is moved from afirst position. where it bears against the electromagnet. into a secondposition. and that in one of its positions blocks the control elementlocated in a terminal position. An actuation mechanism or device actsupon the holding element in order to bring the holding element from itssecond position into its first position and/or to raise the holdingelement bearing against the electromagnet when the electromagnet is notenergized from such electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will he betterunderstood and objects other than those set forth above. will becomeapparent when consideration is given to the following detaileddescription thereof. Such description makes reference to the annexeddrawings wherein:

FIG. I is a schematic view. partially in cross-section. of a firstexemplary embodiment of apparatus designed according to the invention;

FIG. 2 depicts the embodiment of FIG. I in a different position of thecomponents thereof.

FIG. 3 is a second exemplary embodiment of apparatus designed accordingto the invention.

FIG. 4 illustrates the apparatus of FIG. 3 in a different position ofthe components thereof;

FIG. 5 is a schematic view of a third exemplary embodiment of theinvention;

FIGS. 6 and 7 depict the apparatus of FIG. 5 with the components thereofin respectively different positions; and

FIG. 8 is a schematic view depicting a fourth exemplary embodiment ofthe invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Theexemplary embodiments of apparatus depicted in FIGS. I to 7 will beunderstood to each comprise and electromagnet 2 which is mounted at aschematically depicted holding or holder mechanism I. The nonvisiblecoil of each such electromagnet 2 is selectively connected via two coilterminals 3 with a not particularly illustrated suitable voltage source.Excitation of each electromagnet 2 occurs in accordance with a controlprogram.

The armature 4 ofthe electromagnet 2 is constructed as a retaining orholding hook member or element which is pivotably mounted about an axleor shaft 5 at the holding or holder device I. A resilient element. suchas the spring 6 engages with the armature 4. this spring 6 being securedat one end to the holding mechanism or device I. as shown. Spring 6moves the armature 4. when the electromagnets are not energized. out ofa first position where it bears against the associated electromagnet 2,as best seen by referring to FIGS. I. 3 and 5, into a second position.as best seen by referring to FIGS. 2. 4 and 6. where it engages with arecess 7a of a control element 7 and fixedly holds the latter in a firstterminal or end position. This control element 7 is driven to-andtro insynchronism or cycle with a textile machine and between two terminalpositions in any suitable manner. The second terminal position of thecontrol element 7 has been indicated in phantom lines. This controlelement 7 can serve. for instance. to actuate a yarn guide device of atextile machine. as the same has been described in German patentapplication P 22 ()4 814 incorporated herein by reference.

The armature 4 is provided with a nose or dog mem ber 4a with whichcooperates an actuation de\ice. which for the exemplary embodimentsdepicted in FIGS. 1 and 2. 3 and 4 as well as S to 7 respectively. isdifferently constructed.

In particular. with the exemplary embodiment depicted in FIGS. and 2this actuation device or mechanism incorporates a lever 8 which isrotatably mounted at one end about a shaft or axle l0 and at its otherend is supported through the agency of a spring II at the holdingmechanism or device 1. Approximately at the center of the lever 8 thereis rotatably secured thereat a roller or roll 12 which cooperates with arotatably driven control disk or cam I3. By means of the spring I1 thereis achieved the result that the roller 12 will bear against the controlcam surface of the control cam 13. At the end of the lever 8 which isrotatable about the shaft II] this lever 8 carries an actuation ledgemember or rail 9 which acts upon the nose or dog 41:.

The control cam 13 rotates in accordance with the movement ofthe controlelement 7 in cycle or synchronism with the textile machine. If. as shownin FIG. 1. the roller 12 cooperates with the protruding portion 13a ofthe control cam I3, then the lever 8 is raised and rotated into aposition in which the actuation ledge or rail 9 acting upon the nose ordog 4a presses the armature 4 against the electromagnct 2 FIG. I J.During further rotation of the control cam or disk I3 the lever 8 isdownwardly pressed by the spring II and the actuation ledge 9 rotates inclockwise direction out of the position depicted in FIG. I into theposition illustrated in FIG. 2. If at this point in time theelectromagnet 2 is not energized. then the spring 6 pulls the armature 4into its position where it has dropped or moved away from theelectromagnet 2. and which has been shown in FIG. 2. In this positionthe armature 4 engages with the control element 7 which. at this pointin time. is located in its lower end or terminal position and fixedlyretains this control element in such terminal position IFIG. 2).

Now as soon as the portion or part 13a of the control cam 13 againbecomes effective at the roller 12. then the lever 8 is again raised andthe actuation element 9 is rotated in the counterclockwise direction. Inso doing. the actuation element 9 impacts against the nose or dog 41:.with the result that the armature 4 is again brought to bear against theassociated electromagnet 2.

With the electromagnet 2 energized the armature 4 which bearsthereagainst is fixedly held and cannot be moved by the spring 6 awayfrom the electromagnet. The control element 7 is therefore not fixedlyheld in its lower terminal or end position. rather carries out itsto-and-fro movement without obstruction.

Since the armature 4 is brought to bear against the electromagnet 2. outof its position depicted in FIG. 2, by means of the actuation ledge orrail member 9, this electromagnet must not attract the armature 4 out ofits dropped-off position. rather must only fixedly hold the armature 4contacting there-against. Hence. the electromagnet. because it must notcarry out any actual stroke or displacement work. can be correspondinglysmaller dimensioned.

With the exemplary embodiment depicted in FIGS. 3 and 4 the actuationmechanism. analogous to the embodiment depicted and described above withregard to FIGS. I and 2, possesses an actuation lever 8 which isrotatable about a shaft or axle 10, this lever 8 hearing at one endthrough the agency of a spring 11 at the holding or holder mechanism 1.At the lever 8 there is again rotatably mounted a roller 12 which ispressed by spring 11 against the control cam surface or curve of thecontrol disk or control cam 13 which is rotatably driven in synchronismor cycle with the textile machine.

At the end ofthe lever 8 which is rotatable about the shaft N) there ismounted at this lever 8 an actuation ledge or rail member i.e.. anactuation member 14. This actuation ledge or rail member 14, analogousto the actuation ledge or rail member 9 of FIGS. 1 and 2, acts upon thenose or dog member 4a of the armature 4.

how ever in this instance is arranged at the other side of such nosc 40than was the case for the actuation ledge member 9 of FIGS. 1 and 2.

If the armature 4 is located in a position where it has dropped-off ormoved away from the electromagnet 2 (FIG. 4]. then it blocks the controlelement 7 located in its lower terminal or end position. In thisposition the armature 4 is held by the spring 6. Ifthe electromagnet 2is energized. then such attracts the armature 4. so that this arntaturc.as best shown by referring to FIG. 3. comes to bear against theelectromagnet.

As long as the roller I2 bears against the portion or part [3/1 of thecontrol cam surface or control curve. which is defined by the points Aand B. then the actuation ledge or rail member 14 does not act upon thenose or dog 44: (FIG. 3). On the other hand, if the roller 12 is locatedin the recess 13 of the control cam 13. then the lever 8 is rotated bythe spring II, with the result that the actuation ledge or rail member14 rotates in clockwise direction and pushes against the nose or dogmember 4a. The actuation mechanism or device 8. 11,

l2. l3. I4 is constructed in such a way that the actuation ledge memberI4 then pushes against the nose when the armature 4 bears against theelectromagnet 5 2. Since this electromagnet 2. at this point in time, isnot energized. the armature 4 is pushed away from the electromagnet bymeans ofthe actuation ledge member 14 and is rotated by the spring 6into the position depicted in FIG. 4.

Depending upon whether the electromagnet is energized or not, thearmature 4 is located in the one or other position and blocks theassociated control ele ment 7 or does not influence such control elementrespcctively.

The pushing away fo the armature 4 from the nonenergized electromagnet 2by means of the actuation ledge or rail member 14 is particularly ofsignificance in the case of direct-current magnets, since the armature,after de-energizing the excitation coil of the elec tromagnet, remainsadhering at the electromagnet owing to remanence. Now in order to avoiderroneous actuation brought about by the undesired adherence of thearmature 4, this armature is raised or moved from the electromagnet whenthe latter is not energized by means of the actuation ledge or railmember 14.

With the exemplary embodiment depicted in FIGS. 5 to 7 the actuationmechanism is constructed as a combination of the actuation mechanisms ofFIGS. 1 and 2 and that of FIGS. 3 and 4. The actuation lever 8 whichbears at one end via a spring II at the holding mechanism or device 1 isrotatably mounted at its other end about the shaft or axle 10 and atthis end possesses two actuation ledge or rail members i.e.. actuationmembers 9 and 14. These members accommodate therebetween the nose or dog41:. upon which they act depending upon the position of the lever 8. Theposition of the actuation lever 8 is determined by the control cam ordisk 13 which is rotatably driven in synchronism with the textilemachine, this control cam 13 cooperating with a roller 12 which isrotatably secured at the lever 8.

FIG. 5 illustrates the armature 4 in its position where it bears againstthe electromagnet 2, and in which position the armature 4 is moved bythe actuation ledge member or rail member 9 which acts upon the nose 4a.The lever 8 is located in its raised position in which it is rotated bymeans ofthe protruding portion 13a of the control cam 13.

During further rotation ofthe control cam 13 the roller l2 arrives so asto bear against the portion or part 13b of the control cam 13. resultingin rotation of the lever 8 under the action of the spring 11.

Now if the electromagnet 2 is energized. when the armature 4 bearsthereagainst. then this armature 4 is fixedly held in this position anddoes not influence the to-and-fro movement of the control element 7.

On the other hand. ifthe electromagnet 2 is not energized when thearmature 4 bears thereagainst. when the cam surface portion or part 13bcooperates with the roller 12, then the armature 4 under the action ofthe spring 6 can follow the actuation ledge or rail member 9 rotating inclockwise direction and such armature rotates into a position where itdrops off. i.e., moves away from the magnet as such has been depicted inFIG. 6. In this position the armature 4 fixedly holds the controlelement 7 in its lower terminal or end position.

Ill

With further rotation of the control cam I3 the roller 12 drops into therecess I34 (FIG. 7). As a result. the lever Sis still further rotatedand the actuation ledge or rail member 14 presses against the nose ordog 41:. in the event that after deenergization of the magnet 2 thearmature 4 is fixedly held owing to the rcmancnce of the magnet and ishindered in its rotational movement. Due to the action of the actuationledge or rail member 14 upon the nose or dog 4a. the armature 4 ispushed away from the electromagnet 2 and under the action of the spring6 is rotated into its position where it has dropped-off theelectromagnet (FIG. 7).

During further rotation of the control cam or disk I3 the roller 12again travels onto the portion or part 13!) of the control cam 13.bringing about a rotation of the actuation lever 8 in thecounterclockwise direction. In so doing. the lever 8 assumes the sameposition as shown in FIG. 6. The actuation ledge or rail members 9 andI4 respectively. do not act upon the nose or dog member 4a oI- thearmature 4.

As soon as the roller or roll 12 again travels onto the protrudingportion 13a of the control disk I3, then the lever 8 together with theactuation ledge members 9 and 14 are further rotated in thecounterclockwise direction. The actuation ledge member 9 begins to pressagainst the nose or dog 41:. Consequently. the armature 4 is rotatedtowards the electroniagnet 2 until it comes to bear against the magnet.Then during further rotation ofthc cam disk I3 the previously describedcourse of movement repeats.

FIG. 8 illustrates a different exemplary embodiment of the inventionapparatus. An clectromagnet I6 is attached to a holding device ormechanism IS. The armature 17 of the electromagnct is constructed topossess a substantially plate-shaped configuration and carries a plunger18 which is displaceably guided in the holder or holding mechanism I5.At the plunger 18 there engages a spring [9 which is attached to theholding mechanism 15. this spring I9 strives to pull the plunger I8together with the armature plate 17 away from the electromagnet.

At the plunger 18 there is mounted a nose or dog member I811 whichengages in a groove 20a of an actuation lever 20 which is guided in theholding or holder mechanism IS. The groove 20 is bounded or delimited bytwo stops 20b and 200 which act upon the nose or dog I811.

The actuation lever or lever member 20 is supported at one end at aspring 21. At the other or opposite end this lever 20 carries a roller22 which is urged by the spring 21 against the control cam surface of acontrol cam or disk 23 which is rotatably driven in cycle or synchronismwith the textile machine.

The apparatus depicted in FIG. 8 operates in the same manner as theapparatus depicted in FIGS. 5 to 7.

If. as shown in FIG. 8. the protruding cam surface portion or part 2311of the control cam 23 acts upon the roller 22. then the lever 20 isdisplaced against the force of the spring 21 and the stop 20h pressesagainst the cam 18a. with the result that the armature I7 is pressedagainst the electromagnet 16.

In this position of the armature 17. in which it bears at theelectromagnct 16. the free end of the plunger 18 is located externallyof the path ofmovement of a nonillustrated to-and-fro moving drivencontrol element. which corresponds to the control element 7 of FIGS. 1

to 7 inclusive. Consequently. the to-and-fro movement of this controlelement is not influenced.

If the control cam 23 rotates further. then the roller 22 comes to bearagainst the surface portion 23b of the control disk 23. resulting in anaxial displacement of the actuation lever 20 brought about by the spring2I.

If at this point in time the electromagnet I6 with the armature I7bearing thereagainst. is energized. then the armature is fixedly heldand does not follow the movement of the actuation lever 20.

If. however. the elcctromagnet I6 is not energized. then the armature I7and the plunger 18. under the tractive effort or pulling force of thespring [9. follows the displacment movement ofthe actuation lever 20.If. however. the armature I7 remains caught owing to the remanence atthe electromagnet 16, then the stop or impact member 20 presses againstthe nose 18a as soon as the roller 22 falls into the recess 230 of thecontrol cam 23. This brings about lifting-off of the arma ture I7 andpermits axial displacement of the plunger 18.

The actuation lever 20 and also the plunger I8 are shifted untilassuming the phantom line depicted position. in which the plunger blocksthe previously mentioned. although not here particularly illustrated.control element in its one terminal position. as such has been describedin conjunction with the embodiments of FIGS. I to 7.

With the embodiment depicted in FIG. 8 it would be also conceivable toconstruct the plunger 20 at its end in such a way that it blocks thecontrol element in its one terminal position when the armature I7 bearsagainst the electromagnet I6 and in the dropped-off or shifted awayposition of the armature I7. which has been shown in phantom lines. themovement of the control element is not influenced.

If necessary. the one or the other of the stops or im' pact members 20/]and 20( can be omitted at the actuation lever 20 in order to only bringabout a lifting-off or a contact i.e.. pressing-on of the armature 17.

It should be understood that with all ofthe evemplary embodiments thepoint in time of energization and deenergization respectively. of therelevant electromagnets 2 or 16 respectively. must be accommodated tothe movement of the control element 7 and the corresponding rotation ofthe associated control cam or disk I3 and 23 respectively. As alreadypreviously mentioned, both the to-and-fro movement of the controlelement 7 as well as also the rotation ofthe control cam 13 or 23respectively. occurs in synchronism or cycle with the textile machine.

With the described apparatuses it is thus possible to influenceselectively the movement of a control element in the described manner.Depending upon whether the electromagnet is energized or not atpredetermined points in time. the holding element which is constructedas the armature of the clectromagnet selectively blocks the controlelement. for instance a notched bar. in one terminal position.

By means of the actuation device. and as already de scribed. thearmature is moved against the elcctormag net and/or raised-off thedc-energized electromagnet.

If the armature is pressed against the magnet by the actuationmechanism. then such magnet must not be constructed as a stroke ordisplacment magnet. rather only as a holding magnet.

Due to the tnechanical lifting-off of the armature with theelectromagnet not energized there are amided disturbances in operation.which can be brought about b the adherence of the armature at theelectromagnet owing to retnancnce.

While there is show it and described present preferred embodiments ofthe invention. it is to be distinctl un derstood that the invention isnot limited thereto. but ma be otherwise varioush embodied and practicedwithin the scope of the following claims. Accordingly What is claimedis:

1. An apparatus for selectively fixedly holding a substantiallyto-andtro tnoving and driven control element of a textile machine in oneoftwo of its possible terminal positions. comprising a holding elementdefined by an armature of a selectively energizablc electromagnct. saidholding element when the electromagnet is deenergized being movable froma first position in which it bears against the electromagnet into asecond position and wherein in one of its positions said holding element blocks the control element which is located in one terminalposition. an actuation mechanism acting upon the holding element forselectively either bringing the holding element from its second positioninto its first position. lifting-off the holding element which bearsagainst the electromagnet when the electromagnet is decnergized. orcarrying out both ofsuch operations.

2. The apparatus as defined in claim 1. further in eluding at least onespring engaging with the holding element in order to move the holdingelement into its second position when the electromagnct is not energizedand in which second position it blocks the control element.

3. The apparatus as defined in claim 1, further including a shaft forrotatablv mounting the holding element so as to be movable from the oneposition itito the other position. the actuation mechanism comprising alever which is pivotable about said shaft. a control mechanism foradjusting the pivotal position of the lever. at least one actuationelement carried by said lever. said actuation element in predeterminedpivotal positions of the lever acting upon the holding element.

4. The apparatus as defined in claim 3, wherein the actuation element.with the holding element located in its second position, acts upon theholding element and upon pivoting the lever brings about a rotation ofthe holding element into its first position.

5. The apparatus as defined in claim 3, wherein the actuation element.when the holding element bears against the electromagnet. acts upon theholding ele' ment and with the electroniagnet tie-energized duringpivoting of the lever lifts-off the holding clement front theelectromagnet.

6. The apparatus as defined in claim 5, wherein a respective actuationelement is mounted at the lever rotation of the holding element into itsfirst position and for lifting-off the holding element from theelectromagnet respectively.

7. The apparatus as defined in claim 1. wherein the holding element ismovable in a substantially translator v manner from the one into itsother position. and wherein the actuation mechanism possesses anactuation lever which is displaceable in the direction of its lengthwiseaxis. a control mechanism for adjusting the position of the actuationlever. the actuation lever carrying at least one actuation element whichin a predetermined position of the actuation lever acts upon the holdingelement.

8. The apparatus as defined in claim 7, wherein the actuation elementwith the holding element located in its second position acts upon suchholding element and during axial displacement of the actuation elementbrings about a displacement ofthe holding element into its firstposition.

9. The apparatus as defined in claim 7. wherein the actuation element,with the holding element bearing against the electromagnet. acts uponsuch holding element. and with the electromagnet de-energized duringaxial displacement of the actuation lever liftingoff the holding elementfrom the electromagnet.

It). The apparatus as defined in claim 9. wherein a respective actuationelement is mounted at the actuation lever for respectively displacingthe holding element into its first position and for lifting-off theholding eletnent from the electromagnet.

11. The apparatus as defined in claim 3. wherein the control mechanismcomprises a rotatabl driven control cam.

12. The apparatus as defined in claitn 7, wherein the control mechanismcomprises a rotatably driven control cam.

13. The apparatus as defined in claim 1, wherein the holding element isconstructed as a holding hook member which is intended to engage with arecess at the control element.

1. An apparatus for selectively fixedly holding a substantiallyto-and-fro moving and driven control element of a textile machine in oneof two of its possible terminal positions, comprising a holding elementdefined by an armature of a selectively energizable electromagnet, saidholding element when the electromagnet is de-energized being movablefrom a first position in which it bears against the electromagnet into asecond position and wherein in one of its positions said holding elementblocks the control element which is located in one terminal position, anactuation mechanism acting upon the holding element for selectivelyeither bringing the holding element from its second position into itsfirst position, lifting-off the holding element which bears against theelectromagnet when the electromagnet is de-energized, or carrying outboth of such operations.
 2. The apparatus as defined in claim 1, furtherincluding at least one spring engaging with the holding element in orderto move the holding element into its second position when theelectromagnet is not energized and in which second position it blocksthe control element.
 3. The apparatus as defined in claim 1, furtherincluding a shaft for rotatably mounting the holding element so as to bemovable from the one position into the other position, the actuationmechanism comprising a lever which is pivotable about said shaft, acontrol mechanism for adjusting the pivotal position of the lever, atleast one actuation element carried by said lever, said actuationelement in predetermined pivotal positions of the lever acting upon theholding element.
 4. The apparatus as defined in claim 3, wherein theactuation element, with the holding element located in its secondposition, acts upon the holding element and upon pivoting the leverbrings about a rotation of the holding element into its first position.5. The apparatus as defined in claim 3, wherein the actuation element,when the holding element bears against the eLectromagnet, acts upon theholding element and with the electromagnet de-energized during pivotingof the lever lifts-off the holding element from the electromagnet. 6.The apparatus as defined in claim 5, wherein a respective actuationelement is mounted at the lever rotation of the holding element into itsfirst position and for lifting-off the holding element from theelectromagnet respectively.
 7. The apparatus as defined in claim 1,wherein the holding element is movable in a substantially translatorymanner from the one into its other position, and wherein the actuationmechanism possesses an actuation lever which is displaceable in thedirection of its lengthwise axis, a control mechanism for adjusting theposition of the actuation lever, the actuation lever carrying at leastone actuation element which in a predetermined position of the actuationlever acts upon the holding element.
 8. The apparatus as defined inclaim 7, wherein the actuation element with the holding element locatedin its second position acts upon such holding element and during axialdisplacement of the actuation element brings about a displacement of theholding element into its first position.
 9. The apparatus as defined inclaim 7, wherein the actuation element, with the holding element bearingagainst the electromagnet, acts upon such holding element, and with theelectromagnet de-energized during axial displacement of the actuationlever lifting-off the holding element from the electromagnet.
 10. Theapparatus as defined in claim 9, wherein a respective actuation elementis mounted at the actuation lever for respectively displacing theholding element into its first position and for lifting-off the holdingelement from the electromagnet.
 11. The apparatus as defined in claim 3,wherein the control mechanism comprises a rotatably driven control cam.12. The apparatus as defined in claim 7, wherein the control mechanismcomprises a rotatably driven control cam.
 13. The apparatus as definedin claim 1, wherein the holding element is constructed as a holding hookmember which is intended to engage with a recess at the control element.